Abstract: In order to explore the response of yield and appearance quality of Japonica rice germplasm resources to temperature increase and screen out thermotolerance germplasm resources of Japonica rice, 365 core germplasms of Japonica rice from the research in the early stage were used as experimental materials, and the conventional field was used as the control. The artificial greenhouse was used to increase the temperature during the whole growth period, and the plant height, yield components and appearance quality traits of Japonica rice were measured. The results showed that, compared with the control, the growth and development process of Japonica rice was accelerated, the growth period was significantly shortened, and the tiller number was significantly reduced under the whole growth period warming stress. At maturity, under the whole growth period warming stress, the effective panicle number, the primary branch number, seed setting rate and thousand-grain weight decreased significantly or extremely significantly, the grain width and grain thickness increased, the length-width ratio decreased, and the grain was short and round. Compared with the control, the appearance quality deteriorated, the chalky rice rate and chalkiness degree increased significantly, and the grain transparency decreased significantly under the whole growth period warming stress. In addition, it was also found that different yield factors had different responses to warming stress, and the thermotolerance of different Japonica rice varieties was also significantly different. Ten strong thermotolerance Japonica rice germplasms with excellent comprehensive traits were identified and screened by using the key thermotolerance response indexes such as effective panicle number, seed setting rate, chalky rice rate and chalkiness degree, as well as the comprehensive heat tolerance coefficient.

Key words: japonica rice, germplasm resource, warming stress during whole growth period, yield, appearance quality, thermotolerance